Investigating the electrothermal characteristics of a Gate Turn Off thyristor during turn-off using SILVACO ALTAS™

By Gerald E. Vineyard

Abstract

Approved for public release, distribution unlimitedThis thesis presents data from a simulation study of the thermal and electrical characteristics of a Gate Turn Off (GTO) thyristor. At present, most of the research on GTO thyristors has focused on their use in power electronic systems at high switching frequencies. As a result, the behavior of GTO thyristors at very low switching frequencies is not well understood. Previous research projects have shown experimentally that GTO thyristors are capable of interrupting significantly more than their nominal turn-off current rating when used in pulsed power applications at low switching frequencies. This work demonstrates the use of physics-based computer simulation to study the electrothermal turn-off characteristics of a GTO thyristor at low switching frequencies. The computer model used in this project simulated both the electrical and the thermal characteristics of a GTO thyristor and allowed its internal properties - such as current density, electric fields, and lattice temperature - to be investigated. The model was used to track the generation, transfer, and dissipation of energy within the structure of the device and show that the current interruption capability of a GTO thyristor may depend on its switching frequency due to the thermal energy that is generated and stored in the device during turn-off.US Navy (USN) author